The invention relates generally to thermal printers, especially those associated with fuel dispensers, and, more particularly, to the prevention of paper jams in such printers.
Dispensers for gasoline and other fuels have undergone many advances in technology. For example, most modem fuel dispensers are electrically connected to an operating system installed on a computer within the gas station office to enable a customer to pay for the fuel at the dispenser itself using a credit or debit card. Moreover, modern dispensers may also include electronic displays for showing sales data, including price-per-gallon, number of gallons dispensed, and amount of payment due, as well as brief advertisements for services such as car washes. Accordingly, a conventional fuel dispenser system will typically include an external point-of-sale ("POS") controller and a fuel dispenser with various electronics including a magnetic card reader for reading the magnetic stripe of a credit or debit card swiped therethrough, a thermal printer for printing receipts in connection with card purchases, an electronic display, such as an LCD, and a pump controller.
As previously indicated, a modern fuel dispenser typically includes a thermal printer for printing credit and debit card receipts in connection with so-called "pay-at-the-pump" transactions. In a conventional thermal printer, a continuous sheet of paper is stored in a roll and the free end thereof is passed between a roller and a thermal print head. The print head holds the paper against the roller, while simultaneously imprinting the appropriate characters thereon. The printer is contained within a housing having an exit through which the printed receipt exits the printer and is made available to customer.
The paper used with thermal printers is chemically treated and, at high temperatures and high humidity, such as might exist in an unprotected environment, such as a fuel dispenser, can become sticky. If the paper sits in the printer for a long periods of time, for example, 2 to 3 hours, without being moved, it will become difficult, if not impossible, for the motor of the thermal printer to advance the paper, thereby rendering it impossible to provide a purchaser with a receipt, as the coating of the paper will have become adhered to the print head. The obvious result of the foregoing is a paper jam. In view of the fact that many purchasers save such receipts for their records, as well as to reconcile their card statement each month, this situation is unacceptable.
Therefore, what is needed is a method and apparatus for preventing paper jams in thermal printers, especially those installed in fuel dispensers.